It is desirable in a future mobile communication system to alleviate human participation in planning, operating and maintaining a network by introducing a network self-optimization mechanism in which the network optimizes a parameter automatically according to a statistic to reduce the cost of building and operating the network. At present it is desirable to adopt an approach in which UEs could be configured by the network to report something for the purpose of alleviating the workload of a manual drive test. On the other hand, it is also desirable to obtain radio measurement information of an area inaccessible to a normal manual drive test. As ascertained in the R10 protocol of the Long Term Evolution (LTE) system, the architecture of applying the control plane is adopted for a Minimization Drive Test (MDT), and this architecture is advantageous in that an evolved base station (eNB, Evolved NodeB) can control a UE accurately. The architecture of applying the control plane has to adopt Radio Resource Control (RRC) signaling to bear parameters with which the UE is configured by the network and information reported from the UE to the network.
There are two categories of MDT measurement in the prior art:
Immediate MDT: The UE applies MDT measurement and reporting in a connected mode. Reuse the form of Radio Resource Management (RRM) measurement, a report is sent to the eNB or an RNC once a report condition is satisfied.
Logged MDT: The UE applies MDT measurement in an idle mode and subsequently reports it measurement result in a connected mode. The measurement result will be obtained and stored in the UE once a configured trigger condition is satisfied and will be reported to the eNB or an RNC in a subsequent appropriate occasion.
In the prior art, a log configuration of an MDT is transmitted from the network to the UE in a connected mode, using a new configuration method instead of extending the existing RRM measurement.
At the UE side: When the RRC connection is released, the UE will not release the received MDT log configuration but still store it and start the log measurement and collect a measurement result.
At the network side: The network will neither store the information on an MDT context for a logged MDT nor transport the MDT context between the network nodes. The MDT context stored at the network side will be released together with the RRC connection.
If the UE stores a log result for the logged MDT, the UE will report a log available indication, if any, to the network in an RRC Connection Setup Complete message if the UE enters a connected mode. Taking an LTE system as an example, FIG. 1 illustrates an RRC connection establishment process in which the UE will transmit an RRC Connection Setup Complete message to the network upon successful establishment of an RRC connection, where the message carries a bit which indicates whether the UE stores the available log, and the network received the indication can subsequently request the UE to report the MDT measurement log result.
However in the MDT measurement approach in the prior art, the UE with available log information can notify the network side in an RRC Connection Setup Complete message to trigger the network side to obtain the log information of the UE, but if a flow of re-access to another cell (e.g., a handover or connection reestablishment flow) takes place and the log information has not been reported or is reported incompletely at this time, then the target cell can not know whether the UE still has the log to report, thus possibly delaying of a normal report of the MDT log may be occurred.